Bar Graph

Hi,

I am trying to create a graph

"Number of calls/Month"

In my graph I want it to have four bars for each of the following (per month):

1. Incident

2. Problem

3. Work Request

4. Total of above three

I am only able to display bars for:

1. Incident

2. Problem

3. Work Request

I am not able to display "Total of calls" bar on the graph. Is there any way to have this as well?

Thanks

suman